1. Field of the Invention
The present invention relates to pre-insulated piping systems of the type used to convey high temperature fluids and to an improved anchor installation for such systems for anchoring a section of pre-insulated piping to prevent undesired movement thereof.
2. Description of the Prior Art
There are many instances in which insulated pipelines are needed. For example, distributed HVAC (heating, ventilation and air conditioning) applications utilize chilled water for cooling and steam for heating. The chiller and boiler are typically contained in a central location and the chilled water and steam are distributed to other locations. For example, on a school or college campus, the chiller and boiler may be located in a power plant building. The chilled water and steam are distributed to classrooms in separate buildings.
A set of insulated pipelines is used to convey the chilled water from the chiller to other locations and back to the chiller. Another set of insulated pipelines is used to carry the steam from the boiler to the other locations and back to the boiler. The insulated pipelines are usually located underground.
Pre-insulated pipe is conventional and commercially available. There are predominately two types of such piping systems in use: Class-A drainable dryable testable (DDT); and polyurethane or polyisocyanurate “bonded” foam systems. Both of these systems use an inner carrier pipe to convey fluid. Although steel is commonly used for the inner pipe which carries the media to be piped, copper or aluminum or other metals as well as fiberglass, PVC, and similar materials may be utilized, as well. Around the outside of the steel pipe is a layer of insulating foam such as, for example, polyisocyanurate foam. Around the outside of the foam is a jacket of hard thermoplastic (such as high density polyethylene, HDPE). The foam has set up or cured within the outer jacket so as to bond to the jacket and to the inner pipe. The plastic jacket protects the foam from mechanical damage and also provides a water tight seal to prevent corrosion of the steel pipe. In the bonded type system, the foam and outer jacket do not move relative to the inner pipe. In the Class-A type system, on the other hand, the insulated inner pipe is designed to move independently of the associated outer jacket. In fact, there is an air gap between the inner pipe and outer carrier pipe in the class-A type system.
There are various examples in the prior art of the need for “anchoring” such pre-insulated piping systems, either to guard against earth movement or to counteract thermal stresses in the pipe line itself. Also, anchors are generally needed at the entry ports of piping into, for instance, a concrete wall. The concrete wall might be a structural wall or foundation wall of a residential, commercial or industrial building or structure. Another common example is in the area of concrete manholes, valve pits and the like, in which conduits enter and leave the manhole through a sealed “porthole” or point of entry of the conduit into a sidewall or riser section of the manhole. It is generally necessary to anchor the pre-insulated pipeline at a point just prior to entry into the manhole since the sealed porthole does not generally allow for longitudinal movement of the piping.
Despite the advances which have been made in pre-insulated piping systems in recent years, and in particular to anchor points in such systems, a need continues to exist for further improvements.
For example, a need exists to better accommodate the high temperatures which are presently experienced at the location of the steel anchor plate which is used in such anchor assemblies, where the anchor plate contacts the steel carrier pipe and also contacts the surrounding foam insulation, particularly where the steel carrier pipe is carrying high temperature fluids.
Reducing the excess heat present at the anchor point would also prolong the life and increase the effectiveness of the corrosion protective coatings which are conventionally applied to the anchor plate and other metal components of the system.
A need also exists for such an anchor system which utilizes many of the conventionally available materials and manufacturing techniques commonly used in the industry and which is relatively simple in design and economical to implement.